The invention is drawn to a method for the preparation of products which comprise a polymer having a macroreticular structure which includes ionic groups in a large density and from which products are derived which absorb intermolecularly, i.e. inside their molecules, large quantities of water, up to 300 times their weight, and which exhibit a high ability, while in the ground, to promote soil fertility, provide for water consumption needs, while reducing overall water consumption of up to 12 times.
The reduction of water consumption is at present a principal subject of global importance. The formation of deserts in several areas of the planet drives this concern and is associated with the survival of the planet. The increased agricultural production to meet the needs of the food demand of the over-populated planet leads to encroachment of nature and to soil erosion. Thus, the primary goal is to meet the needs of water, in a manner that serves but does not erode nature.
This problem is severely aggravated at present, as the water balance alters, the sea starts covering large areas of fertile land leading to a new topography as the equilibrium between the sea and the land reestablishes. It is hence a primary need to introduce new principles for economizing water usage leading to savings associated both with human consumption as well as with the use of water for agricultural purposes.
The invention, in part, is drawn to products which reduce the amount of water needed for botanical soil thereby leading to water savings in the Earth, in Nature and in Agriculture, thus the invention provides for water economy.
The products which absorb water inside their molecules which are the subject of this invention, are produced following a special crosslinking process for polymers leading to a stable macroreticular structure; such polymers contain active aromatic rings and include polystyrene, hydrogenated SBR, styrene-acrylonitrile and all their co-polymers. As crosslinking agents the dibenzo-X-dimethylbenzene and the sulfonic xe2x80x94SO2, radical are used. The processing is promoted in solutions of the polymer such as in chlorinated hydrocarbon solvents, and in molten phases of the polymers at high temperatures.
The macroreticular polymers as produced in the form of a gel, are practically insoluble and must be subject to processing for the introduction of the ionic groups and for this reason, the macroreticular polymers are subject to a suitable shaping in special cutting equipment where the gel formed is entered in an array of tubes which are one meter long and two to four centimeters in diameter where the gel is cut longitudinally and at its end transversely in three to four centimeter pieces so that discrete particles of dimensions of three by four centimeters are produced. In this form, the pieces are suspended in a solvent and are subsequently subject to sulfonation for the introduction of high density sulfonic groups.
Strong sulfonating agents are utilized in a suspension to introduce sulfonic groups to the aromatic rings of the polymer in a quantity of 1.5-2 moles per mole of the aromatic rings. The sulfonating agents include chlorosulfonic acid, sulfur trioxide and oleum sulfuric acid; the quantity thereof is based on the sulfur trioxide contained therein. Sulfonation is fast and efficient as is the introduction of nitric groups and carboxylic groups, the carboxylic groups can be formed with the use of the co-polymer styrene-acrylonitrile by the hydrolysis of the xe2x80x94CN group. The final shaping to spherical form occurs while the polymer is suspended in the solvent during the sulfonation process. The solvent is decanted and the product is washed with ethyl or propyl alcohol to collect the unreacted chlorosulfonic acid. The product is then neutralized in 30% sodium or potassium hydroxide in a recalculated quantity. Since the product has adsorbed water to a degree of 30-50 times its weight, it is then introduced to a tank which contains a 15-25% sodium chloride solution where the polymer shrinks and the water content reduces to about 10%. The product can also be dehydrated by passing through a 20V electrical field. Finally, the product is heated under vacuum up to 160xc2x0 C. until it is fully dehydrated and freed from the solvent. The marketable product is able to absorb water up to 150-300 times its weight. It has the form of small spheres or leaves depending on the cutting process in the extruder.
In a different preparation process, a 30% solution of chlorosulfonic acid is added to a 10-30% solution of the polymer in a quantity of 2-2.2 moles per mole of benzene rings on the polymer. The solution contains 12% acetic acid as an inhibitor to control the introduction of crosslinking with sulfone groups. As the sulfonation reaction progresses, as measured by the release of hydrogen chloride, an insoluble gel is formed by the macroreticular evolution of the polymer with the formation of sulfone bridges. As the gel is formed (about 4-6 hrs.), the solvent is removed which constitutes its own layer by draining; the gel is then washed with ethanol or propanol to react with the unreacted chlorosulfonic acid and the solution is drained. Finally, the pure gel, which is a non stirrable semisolid, is neutralized with calculated amounts of sodium or potassium hydroxide. Then it is strained and passed through an extruder where it is cut to the desired size and shape of the particles and is then subject to complete neutralization to reduce the size and to deodorize thereby forming a marketable product as previously described.
As already mentioned, hydrogen chloride is formed during the sulfonation reaction with chorosulfonic acid. This chlorosulfonic acid is formed in situ by combining sulfur trioxide with chlorinated solvents. The formation of chlorosulfonic acid is part of the inventive process.
Furthermore, a process has been developed involving phase dispersion conditions during crosslinking of the polymer with the 1,4-dichloromethyl-2,5-dimethylbenzene wherein the solvent 1,2 dichloroethane separates from an equal volume of dense sulfuric acid at a constant temperature of around 50xc2x0 C. during which small spheres are formed. Sulfuric acid is then added to the spheres and the temperature is increased up to 80xc2x0 C., or 1.5-2.0 Mol of chlorosulfonic acid is added at ambient temperatures along with a 12% acetic acid solution to the solvent and, following three hours of stirring, the sulfonation is complete and the product is collected, strained, neutralized, shrunk and deodorized. Finally a product is formed having a high quality of color and spherical shape. In the processing of sulfuric acid and chlorosulfonic acid, straining gives a mixture of solvent and sulfuric acid of a volume of about four cubic meters per ton of product, which must be distilled to collect the solvent and the sulfuric acid for either disposal or reuse.
The present invention, in part, is drawn to products that absorb water intermolecularly following simple immersion of inflated polystyrene into oleum sulfuric acid having a concentration of sulfur trioxide in 20, 30 and 65% with which the polymer is decayed by the sulfur trioxide and large spheres of great uniformity are formed. They exhibit a degree of inflation of 40 to 70 which depends on the degree of inflation of polystyrene. These materials, following 12 hours of maturing, are collected and washed with water. This product is not neutralized but delivered in acidic form and constitutes a product which promotes water economy and fertility in the soil.
In all the above, the process of our invention is described in the form of materials which absorb water intermolecularly and promote fertility to the ground. These products have been studied in terms of activity and the following have been observed:
a) With the addition of these products to the soil, it is possible to have the growth of trees and forests accelerated with 100% survival rates while economizing water on the order of 12 for 120 days;
b) The growth of fruit bearing trees is promoted with an acceleration of growth on the order of 30 to 40%, a biomass production increase of 30 to 50% and a doubling of fruit production;
c) Soil fertility is promoted in problematic, sterile and mountain areas as these materials offer water economy to the ground, and help the growth of greenery and the development of soil biological activity.
These materials which contain water intermolecularly, do not evaporate or leak in the ground, and can be kept in a tank to provide the water needs of plants and of trees, consist of inorganic material to the extent of 72 to 75% where the polymer is only the shell and accounts for only 25-28% of the weight. Thus, these materials have maximum stability in soil where they do not degrade biologically nor are they altered in terms of composition. Thus, the products of the invention can operate for indefinitely long periods of time by absorbing/delivering water in the soil.
As a consequence, the products of the invention, analyzed and described above, constitute means of the highest value and utility in maintaining the natural operation, the promotion of natural growth and the production of food in a sustained manner as they promote soil fertility independently of the quality of the soil and in all types of soil under any conditions.